Release v0.51.261 — Release IC (stage-r11) (#3616)

## Release v0.51.261 — Release IC (stage-r11)

Live Todos panel via an explicit `todo_state` SSE contract.

### Fixed
| Issue/PR | Author | Fix |
|----------|--------|-----|
| #3373 follow-up (#3454) | @v2psv | The Todos side panel now tracks `todo` tool state **live during an active run** instead of staying stale until settle / rolling back on a mid-stream reload. A dedicated `todo_state` SSE event sends a full, redacted, idempotent snapshot on todo-tool completion (no more truncated `tool_complete.preview`); the same `api.todo_state` parser feeds live + cold-load; live snapshots persist into INFLIGHT so reload/reattach restores the panel; cold-load vs INFLIGHT reconciled by timestamp (incl. the `coldTs===0` compressed-session edge); legacy reverse-scan kept as fallback for old servers. |

### Gate
- Full pytest suite: **7692 passed, 0 failed**
- ESLint: CLEAN · ruff: CLEAN · browser-smoke: CLEAN
- Codex (regression): **SAFE TO SHIP** — verified the new `todo_state` SSE handler composes with existing dispatch (no double-subscribe), INFLIGHT persistence is cleared on terminal/cancel (composes with discard_session + turn-journal), timestamp reconciliation can't let a stale local snapshot win, redaction holds, the legacy reverse-scan fallback still works with no double-render, and the `models.py` change is todo-scoped (no CLI-classification interaction).

Co-authored-by: v2psv <v2psv@users.noreply.github.com>

api/streaming.py

@@ -43,6 +43,7 @@ from api.helpers import redact_session_data, _redact_text
 from api.compression_anchor import is_context_compression_marker, visible_messages_for_anchor
 from api.metering import meter
 from api.run_journal import RunJournalWriter
+from api.todo_state import emit_todo_state
 from api.turn_journal import append_turn_journal_event_for_stream
 from api.usage import prompt_cache_hit_percent
 from api.models import (
@@ -4996,6 +4997,35 @@ def _run_agent_streaming(
                         'duration': cb_kwargs.get('duration'),
                         'is_error': bool(cb_kwargs.get('is_error', False)),
                     })
+                    # Mirror the todo tool's in-memory state into a
+                    # dedicated SSE event so the Todos panel can update
+                    # in real-time without waiting for the turn to
+                    # settle. The helper guards on name=='todo', sends
+                    # the full snapshot (idempotent under SSE replay)
+                    # and swallows internal errors so emission never
+                    # breaks tool delivery. Prefer the structured
+                    # `result` kwarg from modern Hermes builds; fall
+                    # back to the truncated `preview` only when the
+                    # callback was invoked without one (older builds).
+                    #
+                    # Graceful degradation on old builds: `preview` is a
+                    # truncated snippet, so its JSON is usually unparseable.
+                    # parse_todo_tool_result() then returns None and NO
+                    # todo_state event is emitted — live panel updates are
+                    # silently unavailable on pre-`result` builds. This is
+                    # intended: the panel still hydrates via cold-load on the
+                    # next session GET; it just won't update mid-stream.
+                    emit_todo_state(
+                        put,
+                        name=name,
+                        function_result=(
+                            cb_kwargs.get('result')
+                            if cb_kwargs.get('result') is not None
+                            else preview
+                        ),
+                        session_id=session_id,
+                        stream_id=stream_id,
+                    )
                     _tool_stats = meter().get_stats()
                     _tool_stats['session_id'] = session_id
                     _tool_stats['usage'] = _live_usage_snapshot()
@@ -5064,6 +5094,20 @@ def _run_agent_streaming(
                             'tid': tool_call_id,
                             'is_error': False,
                         })
+                        # Mirror the todo tool's in-memory state into
+                        # a dedicated SSE event so the Todos panel can
+                        # update in real-time without waiting for the
+                        # turn to settle. See the legacy path above
+                        # for the contract; the helper handles the
+                        # name guard, payload shape, and swallow-all
+                        # error policy.
+                        emit_todo_state(
+                            put,
+                            name=name,
+                            function_result=function_result,
+                            session_id=session_id,
+                            stream_id=stream_id,
+                        )
                     _tool_stats = meter().get_stats()
                     _tool_stats['session_id'] = session_id
                     _tool_stats['usage'] = _live_usage_snapshot()